Re: changing drive letters, I would suggest manually switching the drive letter to something like P: (PortableApps, that's what I did) and doing this on every computer you use.
The computer will remember which drive letter you used for that drive.
No need to fight with reassigned drive letters unless you use a LOT of drives at one time

You'll always know, whatever you have in there, that the drive letters will be correct. Once you properly set up that computer.